Analisis Penerapan ISAK 31 : Interpretasi Atas Ruang Lingkup PSAK 13: Properti Investasi terhadap Perusahaan Penyewaan Base Transceiver Station (BTS) (Studi Kasus Perusahaan Terdaftar BEI Penyewaan Menara BTS) = Analysis the Implementation of ISAK 31 : Interpretation of the Scope of PSAK 13: Investment Property on Base Transceiver Station (BTS) Rental Companies (Case Study of IDX Registered BTS Rental Companies)